1. Field of the Invention
The present invention generally relates to audio sound systems, and more particularly to direction-adjustable audio speaker systems adapted for installation in a vehicle passenger compartment.
2. Description of Related Art
Sound, particularly high frequency sound, has a narrow dispersion band width, and thus, is very directional. In order to optimize sound imaging, high frequency sound must be directed at the listener. Therefore, speaker placement is critical to the quality of an automobile sound system. Unfortunately, conventional audio speakers mounted in vehicle passenger compartments cannot custom-aim sound to the listener.
Every model of vehicle differs in layout and dimension, and thus, no stationary speaker is perfectly suited for every vehicle. Moreover, the conventional positioning of speakers within the passenger compartment further inhibits the ability to custom-aim sound at the listener. Typically, audio speakers mount in vehicle door panels, dashes or rear decks, directing sound towards the roof or the listener's feet.
A number of previous speaker systems have been designed with the purpose of enabling the user to direct high frequency sound towards the listener. For example, U.S. Pat. No. 4,630,303 to Tanno discloses a speaker system for automotive stereo sets including a body housing a high range and a low range speaker, wherein the high range speaker can be moved from a retracted position to an extended position to avoid obstructions such as headrests. A motor and a series of gears used to raise the speaker can also be used to alter the vertical angle of the speaker in an effort to direct the sound toward the occupant of the passenger compartment. Unfortunately, the Tanno system is relatively bulky, complicated and does not provide for the lateral adjustment of the speaker angle.
U.S. Pat. No. 4,441,557 to Kurihara discloses a direction-variable speaker system including a first and a second speaker case, each containing a speaker. A series of springs and gear cams rotates the second speaker case, which usually houses a high range speaker, about its end, out of the plane of the first speaker and locks it in the desired position. In this out of plane position, the second speaker can then be rotated about its longitudinal axis where it locks in a set position for the purpose of directing high range sound to the listener.
Unfortunately, the Kurihara device suffers from a number of drawbacks. Specifically, although providing for a greater degree of adjustability than the Tanno device, the ability of the Kurihara device to direct high frequency sound to the listener is still limited. Initially, since high frequency speakers are designed with a circular sound source, there is some restriction on the ability of the Kurihara device to precisely direct sound due to the fact that the axis of rotation about which the vertical angle of the second speaker is controlled is located at the end of the second speaker case. Perhaps more importantly, however, due to the structural configuration of the Kurihara device when the second speaker case is positioned to direct sound to the passenger, the Kurihara device can only safely be mounted in limited locations in the passenger compartment. That is, because the second speaker case forms a relatively fragile appendage extending from the mounting surface, there is a substantial risk that it will be damaged by passengers or packages within the vehicle passenger compartment unless the device positioned away from areas so inhabited, such as the rear deck of an automobile. Not only does this make it difficult find a desirable location to mount the Kurihara device in convertibles, which often do not have a rear deck, but due the multiplicity of vehicle layouts, may also make it virtually impossible to find a safe location where the device can be mounted and precisely positioned to direct sound on an unobstructed line to the ears of the occupant. Finally, as with the Tanno design, the Kurihara device is relatively complicated, incorporating a variety of moving parts, each of which is subject to failure.
Thus, a need exists for a simple, sturdy speaker system capable of capable of precisely aiming the sound radiating from the speaker towards a listener, which can be utilized in connection with the multiplicity of vehicle passenger compartment layouts now in use.